The present invention relates to copying machines in general, and more particularly to improvements in optical projection systems or projecting means for copying machines.
In presently known copying machines, e.g., in xerographic copying machines, the original to be copied is placed face-down onto a transparent copyboard. This is considered necessary in order to obtain a sharp image of the original on a photosensitive surface, e.g., on the photosensitive surface at the outer side of an endless belt-like or cylindrical conductive backing memeber. Thus, when a relatively thick book or brochure is to be placed onto the copyboard, a selected page (which can be located close to the front cover, in the middle or nearer to the rear cover of the book) is supposed to lie flat against the upper side of the copyboard. Such procedure is cumbersome and time-consuming when the operator desires to make copies of sereral pages because the book must be lifted, the next page selected, and the book again placed onto the copyboard so that each of a series of selected pages abuts against the copyboard. It would be simpler and much faster, at least under certain circumstances, to reproduce successive or selected pages of a book while the information on a selected page faces upwardly because the pages could be turned upon completion of each copying operation while the book would remain on the copyboard. the reproduction of information on successive sheets of a stack of sheets would be equally convenient if the imprinted sides of the sheets could face upwardly since the next copying operation could begin as soon as the topmost sheet is removed from the stack. Moreover, the attendant would be in a position to conveniently mask selected portions of the upper side of a single sheet or of the topmost sheet of a stack of sheets on the copyboard as well as to readily shift the single sheet or the topmost sheet of a stack so that only a selected portion of such sheet would be in requisite position for imaging onto a photosensitive surface.